calibre.srv.errors.JobQueueFull

[Alan Aversa]

Occasionally, Calibre's webserver will crash, and the corresponding UI will freeze.

I get tons of these errors in ~/.cache/calibre/server-log.txt:

Server busy handling request: State: parse_header_line Client: ::1:57960 Request: GET / HTTP/1.1
Traceback (most recent call last):
  File "calibre/srv/loop.py", line 357, in queue_job
  File "calibre/srv/pool.py", line 60, in put_nowait
  File "queue.py", line 223, in put_nowait
  File "queue.py", line 156, in put
queue.Full

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "calibre/srv/loop.py", line 648, in tick
  File "calibre/srv/http_request.py", line 308, in parse_header_line
  File "calibre/srv/web_socket.py", line 279, in finalize_headers
  File "calibre/srv/http_request.py", line 345, in finalize_headers
  File "calibre/srv/http_request.py", line 358, in read_request_body
  File "calibre/srv/http_response.py", line 451, in prepare_response
  File "calibre/srv/loop.py", line 359, in queue_job
calibre.srv.errors.JobQueueFull

Server busy handling request: State: parse_header_line Client: ::1:49482 Request: GET / HTTP/1.1
Traceback (most recent call last):
  File "calibre/srv/loop.py", line 357, in queue_job
  File "calibre/srv/pool.py", line 60, in put_nowait
  File "queue.py", line 223, in put_nowait
  File "queue.py", line 156, in put
queue.Full

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "calibre/srv/loop.py", line 648, in tick
  File "calibre/srv/http_request.py", line 308, in parse_header_line
  File "calibre/srv/web_socket.py", line 279, in finalize_headers
  File "calibre/srv/http_request.py", line 345, in finalize_headers
  File "calibre/srv/http_request.py", line 358, in read_request_body
  File "calibre/srv/http_response.py", line 451, in prepare_response
  File "calibre/srv/loop.py", line 359, in queue_job
calibre.srv.errors.JobQueueFull

see this: https://www.mobileread.com/forums/showthread.php?p=4571176#postcount4571176

[Kovid Goyal (kovid)]

Well yes. Those errors mean you have over a 1000 pending jobs in the
server. The server limits the number of queued jobs to prevent RAM
exhaustion attacks. So this is expected behavior. You need to figure out
what it is you are doing to enqueue so many jobs. Look at the server
logs or keep track of what you are doing when the errors start.